Test of 1-2 AA-AAA 5-Mode 800mA Linear Booster (YJP)

1~2* AA/AAA 5-Mode 800mA Linear Booster LED Flashlight Driver Circuit

Driver is from Fasttech.com

Official specifications:

0.9V~3.6V / 500mA@1.5V / 800mA@3.6V / 17mm
Constant Current: Yes
Driver Type: Boost driver and Linear regulator
Input Voltage: 0.9~3.6 -volt
Output Current: 800 mA
PCB Height (w/o Components): 1.5 mm
Reverse Polarity Protection : No
Flashlight Modes: Hi > Mid > Lo > Strobe > SOS
Mode Count: 5
Mode Memory: No
Depth: 2 mm
Diameter: 17 mm
Product Weight: 1.1 g
Booster driver mode when input voltage is 1.5V or less
Linear regular (constant current) mode when voltage is between 1.8V and 3.6V
Rated at 500mA current output @ 1.5V input
Rated at 800mA current output @ 3.6V input

Measurements

Tested with: Cree XP-G2
Driver diameter 16.8mm
Driver height 5mm
The driver uses boost mode and will be forced into direct drive when voltage is to high.
The driver has high, medium, low, strobe and sos.
No memory, always starts in high.
A short off/on will select next mode.
Medium pwm 550Hz with 40% duty cycle
Low pwm 560Hz with 15% duty cycle
Strobe 7.6Hz with 50% duty cycle

High

1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HL

1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HL

Below 1.5 volt the driver will try to draw a constant current from the battery.
When 1.5 volt is reached the brightness is stabilized, until the voltage reaches Vf of the led.
Above Vf of the led the driver will be in direct drive mode.

1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HLDriver

1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HLDriver

At low voltage the efficiency is low (as always) and a lot of power is lost in the driver.
When the driver stabilizes its output, the power loss goes down, as the current goes down.

1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HLLed

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Starting from 0 volt, the driver turns on at 0.75 volt.

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1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20LHLed

In high mode there is no pwm in the light and only a small amount of high frequency noise.

Medium

1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HL%20medium

1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HL%20medium

Because the driver uses pwm, the shape of this curve looks very much like high mode (With pwm the led is driven at full power, but not all the time).

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1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HL%20mediumDriver

1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HL%20mediumLed

Pwm is at 550Hz.

Low

1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HL%20low

Low mode is also the same, but at even lower currents.

1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HL%20lowDriver

1-2%20AA-AAA%205-Mode%20800mA%20Linear%20Booster%20%28YJP%29%20HL%20lowLed

Pwm is at around 560Hz.

Strobe

Strobe%202.4V

Strobe is at 7.6 Hz. Brightness is at full.

SOS

SOS%202.4V

Brightness is at full.

Conclusion

The driver looks like a good driver for one or two NiMH batteries or a CR123 battery, but cannot safely be used with LiIon.
With one NiMH battery the voltage will be too low to stabilize brightness.
With a maximum current draw of about 2A it is not really a good driver for alkaline batteries.

Notes

How do I test a led driver
List of all tested drivers